Polishing sheet and polishing method

Abstract

To provide a polishing sheet which efficiently polishes a hard material such as a metal product and can form a smooth surface having less irregularity, and can form a uniform smooth surface even when repeatedly polishing the material with the same polishing surface.SOLUTION: A polishing sheet contains a base material, a plurality of three-dimensional elements that contain diamond abrasive grains and a binding material and constitute a polishing surface, and an intermediate layer that is provided between the base material and the three-dimensional elements and joins the base material and the three-dimensional elements. A ratio C2 / C1 of a content C2 of the diamond abrasive grains to a content C1 of the binding material is 0.05 to 1.5 by mass ratio.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abrasive sheet and an abrasive method. [Background technology]

[0002] Conventionally, various abrasives have been considered for forming smooth surfaces on metal products and the like. For example, Patent Documents 1 and 2 describe abrasives equipped with a polishing part having a three-dimensional shape. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 9-502665 [Patent Document 2] Japanese Patent Publication No. 2015-223653 [Overview of the project] [Problems that the invention aims to solve]

[0004] In order to form a uniformly smooth surface on the object to be polished, conventional abrasives typically did not reuse the polished surface after polishing one object; instead, a new polished surface or new abrasive material was used for polishing the next object.

[0005] The present invention aims to provide a polishing sheet and a polishing method that can efficiently polish an object to be polished to form a smooth surface with few irregularities, and can form a uniformly smooth surface even when polishing is performed repeatedly on the same polishing surface. [Means for solving the problem]

[0006] One aspect of the present invention relates to a polishing sheet, which includes a base material, a plurality of three-dimensional elements containing diamond abrasive grains and a binder and constituting a polishing surface, and an intermediate layer provided between the base material and the three-dimensional elements for joining the base material and the three-dimensional elements, wherein the ratio C2 / C1 of the content C2 of the diamond abrasive grains to the content C1 of the binder is 0.05 to 1.5 in terms of mass ratio.

[0007] Another aspect of the present invention relates to a polishing method for polishing a plurality of objects to be polished using the polishing sheet, which includes a first polishing step of pressing the polishing surface of the polishing sheet against the object to be polished and sliding the polishing sheet and the object to be polished, and a reuse step of polishing another object to be polished using at least a part of the polishing surface used in the first polishing step.

Advantages of the Invention

[0008] According to the present invention, there is provided a polishing sheet capable of efficiently polishing an object to be polished to form a smooth surface with few irregularities and forming a uniform smooth surface even when repeated polishing is performed on the same polishing surface. Further, according to the present invention, there is provided a polishing method capable of efficiently polishing an object to be polished using the polishing sheet.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view showing one aspect of the polishing sheet. [Figure 2] It is a cross-sectional view showing another aspect of the polishing sheet. [Figure 3] (a) is a view showing one aspect of the three-dimensional shape of the polishing sheet, and (b) is a view showing another aspect of the three-dimensional shape of the polishing sheet. [Figure 4] (a) is a view showing one aspect of the three-dimensional shape of the polishing sheet, and (b) is a view showing another aspect of the three-dimensional shape of the polishing sheet.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present invention will be described while referring to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted. Also, the drawings are drawn with some exaggeration for easy understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

[0011] (Polishing sheet) The polishing sheet according to the present embodiment includes a base material, diamond abrasive grains and a binder, a plurality of three-dimensional elements constituting a polishing surface, and an intermediate layer provided between the base material and the three-dimensional elements for joining the base material and the three-dimensional elements.

[0012] In the present embodiment, the ratio C2 / C1 (mass ratio) of the content C2 of the diamond abrasive grains to the content C1 of the binder is 0.05 to 1.5.

[0013] The polishing sheet according to the present embodiment can efficiently polish a hard material such as a metal product to form a smooth surface with few irregularities, and can form a uniform smooth surface even when polishing is repeated (for example, 10 times or more) on the same polishing surface. When the ratio C2 / C1 exceeds 1.5, when polishing is repeated on the same polishing surface, the formed smooth surface gradually becomes rough, and it is difficult to form a uniform smooth surface. Also, when the ratio C2 / C1 is less than 0.05, when polishing is repeated on the same polishing surface, the polishing performance greatly decreases, and it becomes difficult to remove irregularities.

[0014] The reasons for the above effects are not entirely clear, but when the ratio C2 / C1 exceeds 1.5, the amount of grinding is large and a lot of polishing debris is generated, and the rigid three-dimensional elements make it difficult to remove polishing debris from the polishing surface. For these reasons, polishing debris tends to adhere to the polishing surface, and this adhered polishing debris is thought to be one of the causes of surface roughness during repeated polishing. On the other hand, when the ratio C2 / C1 is less than 0.05, the small amount of diamond abrasive grains leads to a significant decrease in polishing performance due to wear of the diamond abrasive grains, and it is thought that sufficient polishing performance cannot be maintained during repeated polishing. In other words, when the ratio C2 / C1 is within the above range, the adhesion of polishing debris to the polishing surface is suppressed, and the amount of abrasive grains is sufficient to maintain sufficient polishing performance even during repeated polishing, thus resulting in the above effects.

[0015] A preferred embodiment of the abrasive sheet will be described in detail below with reference to the drawings.

[0016] Figure 1 is a cross-sectional view showing a preferred embodiment of an abrasive sheet. The abrasive sheet 10 shown in Figure 1 comprises a base material 11, three-dimensional elements 12 containing diamond abrasive grains and a binder, and an intermediate layer 13 disposed between the base material 11 and the three-dimensional elements 12, which bonds the three-dimensional elements 12 to one surface of the base material 11.

[0017] Examples of the base material 11 include paper base material, cloth base material, sponge base material, resin film, metal film, and the like.

[0018] Examples of paper substrates include kraft paper, impregnated paper, coated paper, and synthetic paper. Examples of cloth substrates include cotton cloth, rayon cloth, polyester cloth, or blends thereof. Examples of sponge substrates include polyurethane foam, polyethylene foam, and melamine foam.

[0019] The substrate 11 preferably has a smooth surface in contact with the intermediate layer 13, and from the viewpoint of easily obtaining smoothness, it is preferable to include a resin film and / or a metal film. Examples of resin films include polyester film, polyimide film, and polyamide film. From the viewpoint of high thermal conductivity and expected frictional heat dissipation, metal foil is preferred as the metal film, and examples of metal films include aluminum foil and copper foil. The substrate 11 may be a laminate formed by laminating a plurality of resin films, a laminate formed by laminating a plurality of metal films, or a laminate containing both a resin film and a metal film.

[0020] The surface of the base material 11 opposite to the intermediate layer 13 may be surface-treated, for example, to improve its adaptability to polishing equipment. Examples of such surface treatments include roughening by sandblasting, forming an anti-slip layer with an inorganic particle-containing resin, and applying an adhesive layer with a pressure-sensitive adhesive.

[0021] The thickness of the base material 11 is not particularly limited and may be, for example, 15 μm or more, or 60 μm or more. Alternatively, the thickness of the base material 11 may be, for example, 500 μm or less, or 350 μm or less. Increasing the thickness of the base material 11 significantly suppresses damage to the base material during high-load polishing, improving the stability of high-load polishing. Conversely, decreasing the thickness of the base material 11 further improves its ability to conform to the workpiece being polished.

[0022] The substrate 11 has a Young's modulus of 3.0 × 10 at 25°C. 9 It is preferable that the Pa is greater than or equal to Pa. Having such a base material 11 makes it easier to slide the abrasive sheet 10 against the fixed hard material, resulting in an abrasive sheet 10 with excellent adaptability to high-load polishing.

[0023] The Young's modulus of the substrate 11 at 25°C is set to 3.5 × 10⁻⁶ from the viewpoint of obtaining the above effect more significantly. 9 Pa or higher is more preferable, 3.8 × 10 9More preferably, it is above Pa. When the base material 11 is a metal film, the Young's modulus of the base material 11 at 25°C may be even higher, for example, 10×10 9 Pa or more, and may be 20×10 9 Pa or more.

[0024] The upper limit of the Young's modulus of the base material 11 at 25°C is not particularly limited. From the perspective of the processability into a roll-shaped product, the Young's modulus of the base material 11 at 25°C is, for example, 250×10 9 Pa or less is preferable, and 150×10 9 Pa or less is more preferable. When the base material 11 is a resin film, the Young's modulus of the base material 11 at 25°C may be even lower, for example, 20×10[[ID=!3]]] 9 Pa or less, and may be 15×10 9 Pa or less.

[0025] In this specification, the Young's modulus of the base material indicates a value measured by a test on the tensile properties of the film in accordance with ISO 527-3.

[0026] The base material 11 preferably has an elongation at break of 200% or less. Such a base material 11 can fix the three-dimensional element 12 more firmly during high-load polishing, and the polishing performance tends to be further improved.

[0027] From the perspective of obtaining the above effects more significantly, the elongation at break of the base material 11 is more preferably 180% or less, and even more preferably 150% or less. When the base material 11 is a metal film, the elongation at break of the base material 11 may be even lower, for example, 40% or less, and may be 30% or less.

[0028] The lower limit of the elongation at break of the base material 11 is not particularly limited, and may be, for example, 1% or more, and may be 3% or more. When the base material 11 is a resin film, the elongation at break of the base material 11 may be even higher, for example, 20% or more, and may be 40% or more.

[0029] In this specification, the elongation at break of the substrate is expressed as a value measured in accordance with JIS K 7127.

[0030] The three-dimensional element 12 contains diamond abrasive grains (hereinafter also simply referred to as abrasive grains) for polishing the object to be polished, and a binder for binding the abrasive grains together. The three-dimensional element 12 creates a protrusion on the polishing surface of the polishing sheet 10 that contacts the object to be polished and a recess that does not contact the object to be polished. In other words, the three-dimensional element 12 in the polishing sheet 10 can be described as an element provided such that the polishing surface has both a protrusion and a recess.

[0031] The polishing sheet 10 has multiple three-dimensional elements 12, and these three-dimensional elements 12 are independent of each other. With this configuration, the multiple three-dimensional elements 12 can each follow the irregularities of the object being polished during high-load polishing.

[0032] The average particle size of the abrasive grains may be appropriately selected depending on the application of the abrasive sheet 10. The average particle size of the abrasive grains may be, for example, 2 μm or more, preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 9 μm or more. A larger average particle size of the abrasive grains makes it easier to manufacture an abrasive sheet that satisfies the ratio C2 / C1 described later. Alternatively, the average particle size of the abrasive grains may be, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0033] In this specification, the average particle size of the abrasive particles is the volume cumulative particle size D50 measured using laser diffraction / scattering particle size distribution measurement. The specific measurement conditions are as follows, but this does not preclude the use of other measuring devices and conditions as long as it is understandable to those skilled in the art that equivalent values ​​can be obtained based on similar principles. • Measurement device: Laser diffraction / scattering particle size distribution analyzer LA-920 (Horiba, Ltd., Kyoto City, Kyoto Prefecture) • Analysis software: LA-920 for Windows (registered trademark) • Abrasive particle size: 150mg • Dispersion medium: 150 mL of deionized water • Circulation speed (water stirring speed): Set value 15 • Ultrasonic oscillation: Yes (uses the ultrasonic device built into the LA-920) ·Measurement temperature: Room temperature (25℃) • Relative humidity: 85% or less • He-Ne laser light transmittance: 85% Tungsten lamp transmittance: 85% • Relative refractive index: set to 1.80 (Relative refractive index of diamond: 1.81) • Measurement time: 20 seconds • Number of data entries: 10 • Particle size standard: volume

[0034] The grit size of the abrasive grains is defined in JIS R-6001-2:2017 and may be, for example, #240 to #20000, preferably #400 to #2000.

[0035] The binder can be described as a matrix that disperses the abrasive particles. The binder may be, for example, a cured product of a thermosetting resin composition, or a cured product of a photocurable resin composition.

[0036] The binder has a Young's modulus of 1.0 × 10 at 25°C. 9 It is preferable that the Pa is greater than or equal to Pa. With such a binder, the shape of the three-dimensional element 12 can be sufficiently maintained even under high load, and the polishing force on the object to be polished tends to be more pronounced.

[0037] From the perspective of obtaining the above effect more significantly, the Young's modulus of the binder at 25°C should be 2.0 × 10⁻⁶. 9 Pa or higher is more preferable, 4.0 × 10 9 A Young's modulus of Pa or higher is even more preferable. The upper limit of the Young's modulus of the binder at 25°C is not particularly limited, for example, 20 × 10 9 It may be less than or equal to Pa, 15 × 10 9 Please refer to the following below Pa.

[0038] In this specification, the Young's modulus of the binder is expressed as the value of the complex modulus calculated from the results of a dynamic viscoelastic measurement using bending vibration at a frequency of 1 Hz in accordance with ISO 6721-5, under the following conditions. (Measurement conditions) ·Measurement device: Solids Analyzer RSA III manufactured by Rheometric Scientific • Measurement mode: Three-point bending ·Distance between support ends: 40mm • Frequency: 1Hz • Approximate dimensions of the test specimen: 10mm wide x 50mm long x 2mm thick ·Distortion: 0.05%

[0039] In one preferred embodiment, the binder may contain a phenolic resin. Such a binder is likely to yield the preferred Young's modulus described above.

[0040] In another preferred embodiment, the binder may be a cured product of a resin composition containing an acrylic monomer. The acrylic monomer is a compound having at least one polymerizable group selected from the group consisting of an acryloyl group and a methacryloyl group. The resin composition is cured by polymerization of the acrylic monomer to form a cured product constituting the binder.

[0041] The above resin composition may contain, in which 60% by mass or more of the acrylic monomer is a polyfunctional monomer selected from the group consisting of tris(2-hydroxyethyl) isocyanurate triacrylate and tris(2-hydroxyethyl) isocyanurate diacrylate. This forms a binder with a high compressive yield stress, which allows the binder to be deformed while maintaining the pressure applied to the polished surface during high-load polishing, improving adhesion to hard materials and achieving high polishing power.

[0042] The content of the above-mentioned polyfunctional monomer in the acrylic monomer is preferably 65% ​​by mass or more, more preferably 85% by mass or more, may be 95% by mass or more, may be 99% by mass or more, or may be 100% by mass or more.

[0043] The above resin composition may further contain other acrylic monomers other than the above polyfunctional monomer. Preferably, the other acrylic monomers have a glass transition temperature of 25°C or higher in their homopolymer form. Examples of other acrylic monomers include, as monofunctional monomers, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, etc.; as difunctional monomers, tricyclodecane methanol di(meth)acrylate, bisphenol A ethylene oxide modified di(meth)acrylate, etc.; and as polyfunctional monomers, trimethylpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ε-caprolactone modified tris-(2-acryloxyethyl) isocyanurate, etc.

[0044] The acrylic monomer content in the above resin composition may be, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more, based on the total amount of solids in the resin composition. There is no particular upper limit to the acrylic monomer content in the above resin composition.

[0045] The above resin composition may further contain a polymerization initiator for initiating the polymerization of the acrylic monomer. Examples of polymerization initiators include thermal polymerization initiators and photopolymerization initiators, of which photopolymerization initiators for initiating free radical polymerization are preferred. Examples of photopolymerization initiators include intramolecular cleavage type initiators such as benzoin derivatives, benzyl ketals, α-hydroxyacetophenone, α-aminoacetophenone, acylphosphine oxides, titanocenes, and O-acyloximes, and examples of hydrogen abstraction type initiators such as benzophenone, Michler ketone, and thioxanthone.

[0046] The content of the polymerization initiator in the above resin composition may be appropriately changed depending on the type of polymerization initiator. The content of the polymerization initiator in the above resin composition may be, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of acrylic monomer. Alternatively, the content of the polymerization initiator in the above resin composition may be, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of acrylic monomer.

[0047] The above resin composition may further contain other components besides acrylic monomer and polymerization initiator. Examples of other components include coupling agents, wetting agents, dyes, pigments, plasticizers, fillers, release agents, polishing aids, and other additives.

[0048] In the three-dimensional element 12, the ratio of the abrasive content C2 to the binder content C1, C2 / C1 (mass ratio), is 0.05 or more, preferably 0.1 or more. Furthermore, the ratio C2 / C1 (mass ratio) is 1.5 or less, and from the viewpoint of obtaining the above effect more significantly, it is preferably 1.0 or less, and more preferably 0.7 or less. Also, from the viewpoint of reducing the amount of diamond used and lowering costs, the ratio C2 / C1 (mass ratio) may be, for example, 1.5 or less, 1.0 or less, 0.7 or less, 0.5 or less, or 0.2 or less.

[0049] When the three-dimensional element 12 is divided into a top portion 12a on the side opposite to the base material 11, which accounts for 20% of the volume of the three-dimensional element 12, and a base portion 12b on the side of the base material 11, which accounts for 80% of the volume of the three-dimensional element 12, it is preferable that 50% or more of the mass of abrasive grains in the three-dimensional element 12 are located in the top portion 12a.

[0050] As described above, a higher abrasive content in the top portion 12a allows for efficient polishing performance with a smaller amount of abrasive, resulting in a more pronounced effect. More specifically, since the top portion 12a constitutes the polishing surface, the selective presence of abrasives in the top portion 12a enables high polishing performance even with a small amount of abrasive. Furthermore, since the base portion 12b constitutes a groove for discharging polishing debris, a lower abrasive content improves the discharging efficiency of polishing debris, further suppresses the adhesion of polishing debris to the polishing surface, and makes it easier to obtain a more uniform and smooth surface.

[0051] From the viewpoint of obtaining the above effects more significantly, the amount of abrasive grains contained in the top portion 12a is more preferably 55% by mass or more of the abrasive grains in the three-dimensional element 12, and more preferably 60% by mass or more.

[0052] In Figure 1, the three-dimensional element 12 is described as having a triangular cross-section, but the shape of the three-dimensional element 12 is not necessarily limited to this. For example, the three-dimensional element 12 may have a conical structure with a convex portion as its apex and joining with the intermediate layer 13 at its base. Alternatively, the three-dimensional element 12 may have a triangular prism structure with a convex portion on one side and joining with the intermediate layer 13 on the side opposite to that side.

[0053] Furthermore, the three-dimensional element 12 may have a columnar structure, for example, with a convex portion on one base and joined to the intermediate layer 13 on the other base. Alternatively, the three-dimensional element 12 may have a frustum structure, for example, with a convex portion on one base and joined to the intermediate layer 13 on the other base.

[0054] The three-dimensional element 12 may have a multilayer structure. For example, the three-dimensional element 12 may consist of an abrasive layer made of abrasive particles and a binder, and a support layer made of a binder.

[0055] The height of the three-dimensional element 12 (height from the recess to the protrusion on the polished surface) may be, for example, 2 to 800 μm, or 4 to 400 μm.

[0056] The intermediate layer 13 is placed between the base material 11 and the three-dimensional element 12, and is a layer that joins the base material 11 and the three-dimensional element 12.

[0057] The Young's modulus of the intermediate layer 13 at 25°C is 1.0 × 10⁻⁶. 7 It is preferable that the Pa is greater than or equal to Pa. Since such an intermediate layer 13 can sufficiently fix the three-dimensional elements 12 on the substrate 11, it can sufficiently suppress the detachment of the three-dimensional elements 12 during polishing.

[0058] From the perspective of achieving the above effect more significantly, the Young's modulus of the intermediate layer 13 at 25°C is 3.0 × 10⁻⁶. 7 Pa or higher is preferred, 5.0 × 10 7 Pa or higher is preferable.

[0059] Furthermore, the Young's modulus of the intermediate layer 13 at 25°C is 5.0 × 10⁻⁶. 8 It is preferable that the pressure is Pa or less. Such an intermediate layer 13 functions as a buffer layer during high-load polishing, allowing each of the multiple three-dimensional elements 12 to conform to the irregularities of the object being polished. Therefore, with such an intermediate layer 13, a smooth surface with few irregularities can be easily formed.

[0060] From the perspective of achieving the above effect more significantly, the Young's modulus of the intermediate layer 13 at 25°C is 4.0 × 10⁻⁶. 8 Preferably Pa or less, 2.0 × 10 8 Pa or lower is more preferable.

[0061] The Young's modulus of the intermediate layer is the value of the complex modulus calculated from the results of a dynamic viscoelasticity measurement using bending vibration at a frequency of 1 Hz in accordance with ISO 6721-5, under the following conditions. (Measurement conditions) ·Measurement device: Solids Analyzer RSA III manufactured by Rheometric Scientific • Measurement mode: Three-point bending ·Distance between support ends: 40mm • Frequency: 1Hz • Approximate dimensions of the test specimen: 10mm wide x 50mm long x 2mm thick ·Distortion: 0.05%

[0062] The constituent material of the intermediate layer 13 is not particularly limited as long as it can bond the base material 11 and the three-dimensional element 12. The intermediate layer 13 may be composed of, for example, a cured product of a thermosetting resin composition, or a cured product of a photocurable resin composition.

[0063] In one preferred embodiment, the intermediate layer 13 may be composed of a cured product of a resin composition containing urethane acrylate. Such an intermediate layer 13 tends to easily achieve both the preferred Young's modulus described above and strong adhesion between the substrate 11 and the three-dimensional elements 12.

[0064] Urethane acrylate can be defined as a polymerizable compound having a urethane bond and at least one polymerizable group selected from the group consisting of acryloyl groups and methacryloyl groups. Specific examples of urethane acrylate include, for example, polyester skeleton-containing urethane acrylate, polyether skeleton-containing urethane acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, and the like.

[0065] The above resin composition may further contain other polymerizable compounds besides urethane acrylate. The other polymerizable compounds may be appropriately selected from compounds copolymerizable with urethane acrylate. Examples of other polymerizable compounds include tetrahydrofurfuryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclic trimethylolpropane formal acrylate, glycidyl methacrylate, and (meth)acrylic acid. Furthermore, the above resin composition may further contain polymerizable compounds that do not copolymerize with urethane acrylate, such as epoxy resins.

[0066] The proportion of urethane acrylate in the polymerizable compound in the above resin composition may be, for example, 40% by mass or more, preferably 50% by mass or more, and more preferably 70% by mass or more. This makes it easier to obtain the preferred Young's modulus mentioned above.

[0067] The upper limit of the proportion of urethane acrylate in the polymerizable compound in the above resin composition is not particularly limited and may be, for example, 99.9% by mass or less, or 99% by mass or less.

[0068] The above resin composition may further contain a polymerization initiator for initiating the polymerization of urethane acrylate. Examples of polymerization initiators include thermal polymerization initiators and photopolymerization initiators, of which photopolymerization initiators for initiating free radical polymerization are preferred. Examples of photopolymerization initiators include intramolecular cleavage type initiators such as benzoin derivatives, benzyl ketal, α-hydroxyacetophenone, α-aminoacetophenone, acylphosphine oxide, titanocenes, and O-acyloximes, and examples of hydrogen abstraction type initiators such as benzophenone, Michler ketone, and thioxanthone.

[0069] The content of the polymerization initiator in the above resin composition may be appropriately changed depending on the type of polymerization initiator. The content of the polymerization initiator in the above resin composition may be, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of the polymerizable compound. Alternatively, the content of the polymerization initiator in the above resin composition may be, for example, 50 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the polymerizable compound.

[0070] The above resin composition may further contain other components besides polymerizable compounds and curing agents. Examples of other components include coupling agents, wetting agents, dyes, pigments, plasticizers, fillers, and other additives.

[0071] In the abrasive sheet 10, the intermediate layer 13 is three-dimensionally molded together with the three-dimensional element 12, forming a recess on the abrasive surface. The abrasive sheet 10 also has multiple intermediate layers 13, each of which joins one three-dimensional element 12 to the base material 11. In other words, in the abrasive sheet 10, one three-dimensional element 12 is provided on one intermediate layer 13.

[0072] In this embodiment, the shape of the intermediate layer is not limited to the shape described above. For example, the abrasive sheet may have multiple three-dimensional elements joined together by a single intermediate layer. In other words, multiple three-dimensional elements may be provided on a single intermediate layer.

[0073] In this embodiment, the total volume of the three-dimensional elements relative to the sum of the three-dimensional elements and the intermediate layer is, for example, 55 volume% or more, preferably 60 volume% or more, and more preferably 70 volume% or more. This tends to extend the lifespan of the abrasive sheet. Alternatively, the total volume of the three-dimensional elements relative to the sum of the three-dimensional elements and the intermediate layer is, for example, 95 volume% or less, preferably 90 volume% or less, and more preferably 85 volume% or less. This improves the adhesion between the substrate and the intermediate layer, and between the intermediate layer and the three-dimensional elements, resulting in a more stable abrasive force of the abrasive sheet and making it easier to obtain a uniform smooth surface.

[0074] Figure 2 is a cross-sectional view showing another embodiment of the abrasive sheet. The abrasive sheet 20 shown in Figure 2 comprises a base material 21, a plurality of three-dimensional elements 22, and an intermediate layer 23 disposed between the base material 11 and the plurality of three-dimensional elements 22, joining the base material 11 and the plurality of three-dimensional elements. The intermediate layer 23 is joined to the base material 11 on one side and to the plurality of three-dimensional elements 22 on the other side. The side of the intermediate layer 23 that is in contact with the three-dimensional elements 22 is three-dimensionally molded together with the three-dimensional elements 22, forming a recess on the abrasive surface.

[0075] The base material 21 and the three-dimensional element 22 may be the same as the base material 11 and the three-dimensional element 12 in the abrasive sheet 10, and the intermediate layer 23 may be the same as the intermediate layer 23 in the abrasive sheet 10 except for its shape. When the three-dimensional element 22 is divided into a top portion 22a that occupies 20 volume percent of the three-dimensional element 22 and a base portion 22b that occupies 80 volume percent of the three-dimensional element 22, it is preferable that 50 mass or more of the abrasive grains in the three-dimensional element 22 are located in the top portion 22a.

[0076] Although the intermediate layer 23 is molded three-dimensionally together with the three-dimensional elements 22 and forms a three-dimensional shape on the polished surface, the intermediate layer 23 does not necessarily need to be molded three-dimensionally, and the three-dimensional elements 22 may be provided on the smooth surface of the intermediate layer 23.

[0077] In this embodiment, a three-dimensional shape is formed on the polishing surface of the polishing sheet by three-dimensional elements (and, in some cases, three-dimensional elements and an intermediate layer). Hereinafter, with reference to the drawings, examples of preferred embodiments of this three-dimensional shape will be given.

[0078] Figure 3(a) is a top view showing one aspect of the three-dimensional shape of the abrasive sheet. The three-dimensional portion 121 has a conical structure (triangular pyramidal structure) with a convex vertex and a base that is joined to the substrate side. In Figure 3(a), the multiple three-dimensional portions 121 are in contact with each other at the base of the conical structure, but the multiple three-dimensional portions 121 may be spaced apart from each other.

[0079] In Figure 3(a), the symbol o indicates the base length of the three-dimensional portion 121, and the symbol p indicates the distance between the vertices of adjacent three-dimensional portions 121. o may be, for example, 5 μm to 1000 μm, preferably 10 μm to 500 μm. p may be, for example, 5 μm to 1000 μm, preferably 10 μm to 500 μm.

[0080] Figure 3(b) is a top view showing another aspect of the three-dimensional shape of the abrasive sheet. The three-dimensional portion 122 has a frustum structure in which one bottom surface forms a convex portion and the other bottom surface is joined to the substrate side. In Figure 3(b), the multiple three-dimensional portions 122 are spaced apart from each other, but the multiple three-dimensional portions 122 may be in contact with each other at the bottom edges on the substrate side.

[0081] In Figure 3(b), the symbol o indicates the base length of the three-dimensional portion 122 on the substrate side, the symbol u indicates the distance between the bases of adjacent three-dimensional portions 122, and the symbol y indicates the base length of the convex side of the three-dimensional portion 122. o may be, for example, 5 μm to 2000 μm, preferably 10 μm to 1000 μm. u may be, for example, 0 to 1000 μm, preferably 2 μm to 500 μm. y may be, for example, 0.5 μm to 1800 μm, preferably 1 μm to 900 μm.

[0082] Figure 4(a) is a perspective cross-sectional view showing another aspect of the three-dimensional shape of the abrasive sheet. The three-dimensional portion 123 has a triangular prism structure in which one side is convex and the side opposite to the convex side is joined to the base material. The three-dimensional portion 123 has a multilayer structure including three-dimensional elements 132 and an intermediate layer 133. When the three-dimensional element 132 is divided into a top portion 132a which accounts for 20% of the volume of the three-dimensional element 132 and a base portion 132b which accounts for 80% of the volume of the three-dimensional element 132, it is preferable that 50% or more of the mass of abrasive grains in the three-dimensional element 132 are located in the top portion 132a.

[0083] Although Figure 4(a) illustrates three-dimensional elements having a triangular prism structure and a multilayer structure, the three-dimensional part having a triangular prism structure may not have a multilayer structure and may consist only of three-dimensional elements.

[0084] The vertex angle α of the three-dimensional part 123 may be, for example, 30° to 150°, or 45° to 140°. In Figure 4(a), the symbol h indicates the height of the three-dimensional part 123, and the symbol s indicates the height of the three-dimensional element 132. h may be, for example, 10 μm to 10,000 μm, preferably 20 μm to 1,000 μm. s may be, for example, 5% to 95% of the height h of the three-dimensional part, preferably 10% to 90%.

[0085] In Figure 4(a), the symbol w indicates the length of the short base of the three-dimensional part 123 (width of the three-dimensional part 123), the symbol p indicates the distance between the vertices of the three-dimensional parts 123, and the symbol u indicates the distance between the long bases of adjacent three-dimensional parts 123. w may be, for example, 2 μm to 2000 μm, preferably 4 μm to 1000 μm. p may be, for example, 2 μm to 4000 μm, preferably 4 μm to 2000 μm. u may be, for example, 0 to 2000 μm, preferably 0 to 1000 μm.

[0086] The length of the three-dimensional portion 123 (length of the long base) may extend over the entire area of ​​the abrasive sheet. In this case, both ends of the three-dimensional portion 123 in the direction of the long base are located near the edge of the abrasive sheet, and multiple three-dimensional portions 123 are arranged in a striped pattern.

[0087] Furthermore, the length of the long base of the three-dimensional portion 123 may be set to an appropriate length, for example, 5 μm to 10,000 μm. An example of this case is shown in Figure 4(b). In Figure 4(b), the end face of the three-dimensional portion 124 is shaped as if it has been cut off at an acute angle from below, but the end face of the three-dimensional portion 124 is not limited to this shape.

[0088] In Figure 4(b), the symbol l indicates the length of the long base of the three-dimensional portion 124, and the symbol x indicates the distance between the short bases of adjacent three-dimensional portions 124. l may be, for example, 5 μm to 10,000 μm, and preferably 10 μm to 5,000 μm. x may be, for example, 0 to 2,000 μm, and preferably 0 to 1,000 μm.

[0089] The abrasive sheet according to this embodiment can sufficiently reduce surface irregularities when polishing under high load. Therefore, the abrasive sheet can be suitably used for high-load polishing applications. In other words, the abrasive sheet may be an abrasive sheet for high-load polishing.

[0090] The load in high-load grinding is, for example, 1.0 × 10⁻⁶. 6 It may be Pa or higher, and 1.2 × 10 6 Pa or higher is preferred, and 1.5 × 10 6 A load of Pa or higher is even more preferable. Furthermore, the load in high-load polishing is, for example, 5.0 × 10⁻⁶. 6 It may be less than or equal to Pa, and 3.0 × 10 6 Pa or less is preferable.

[0091] Furthermore, since the abrasive sheet according to this embodiment is suitable for high-load polishing, it can be suitably used for polishing hard materials such as metal products. In other words, the abrasive sheet may be an abrasive sheet for polishing hard materials.

[0092] Hard materials refer to materials with a Vickers hardness of HV150 or higher, as defined in ISO 8486-2:2007. Examples of hard materials include carbon steel, stainless steel, titanium, tungsten, and ceramic materials such as silicon carbide, aluminum nitride, zirconia, and alumina.

[0093] (polishing method) The polishing method according to this embodiment is a polishing method for polishing multiple objects to be polished using the polishing sheet described above. The polishing method according to this embodiment includes a first polishing step in which the polishing surface of the polishing sheet is pressed against the objects to be polished and the polishing sheet and the objects to be polished are slid, and a reuse step in which at least a portion of the polishing surface used in the first polishing step is used to polish other objects to be polished.

[0094] In the first polishing process, the load applied when pressing the polishing sheet against the object to be polished is, for example, 1.0 × 10 6 The load may be high, exceeding Pa. For example, the load may be 1.2 × 10⁻⁶. 6Pa or higher is preferred, and 1.5 × 10 6 A load of Pa or higher is even more preferable. The upper limit of the load is, for example, 5.0 × 10⁻⁶. 6 It may be less than or equal to Pa, and 3.0 × 10 6 Pa or less is preferable.

[0095] The sliding motion between the abrasive sheet and the object to be polished may be performed by fixing one and sliding the other, or by sliding both. In this embodiment, the method of fixing the object to be polished and sliding the abrasive sheet is particularly preferred.

[0096] The object to be polished is not particularly limited, but from the viewpoint of obtaining a significant effect from using the above-mentioned polishing sheet, it is preferable that it be the hard material described above.

[0097] In this embodiment, a lubricant may be used when sliding the abrasive sheet against the object to be abraded. Lubricants are broadly classified into water-soluble and water-insoluble types. Water-soluble lubricants include soluble type, solution type, and emulsion type, and any of these may be used. Water-insoluble lubricants include those composed of mineral oil and / or fatty oil, and these lubricants may or may not contain extreme pressure additives.

[0098] In this embodiment, by performing the reuse process multiple times (for example, 10 or more times, preferably 15 or more times, more preferably 20 or more times), multiple objects to be polished (for example, 10, preferably 15 or more times, more preferably 20 or more) may be polished on the same polishing surface. The polishing method in the reuse process may be the same as that of the first polishing process.

[0099] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Examples]

[0100] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0101] (Example A-1) <Preparation of compositions for forming three-dimensional elements> A composition for forming stereochemical elements was prepared by mixing 62.33 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, manufactured by Arkema), 0.06 parts by mass of silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), 1.25 parts by mass of photopolymerization initiator (Omunirad 819, manufactured by IGM Resins), 0.62 parts by mass of photopolymerization initiator (Omunirad 369, manufactured by IGM Resins), 5.52 parts by mass of diamond abrasive particles (average particle size 15 μm), and 30.22 parts by mass of propylene glycol methyl ether. The ratio of the diamond abrasive content to the resin content in the composition was 0.09.

[0102] <Preparation of composition for forming the intermediate layer> An intermediate layer-forming composition was prepared by mixing 78.43 parts by mass of urethane acrylate (CN991, manufactured by Arkema), 19.61 parts by mass of acrylate monomer (Biscoat #150, manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 1.96 parts by mass of photopolymerization initiator (Omunirad 819, manufactured by IGM Resins).

[0103] <Preparation of base material> A PET film (125 μm thick, Young's modulus at 25°C: 5.0 MPa) was prepared as the substrate.

[0104] <Preparation of abrasive sheets> A polypropylene shaping film was prepared, having recesses on its surface corresponding to the three-dimensional shape shown in Figure 3(a). The three-dimensional element forming composition was applied to the shaping film using a bar coater, filling the recesses of the shaping film with the composition. The composition filled into the recesses was then dried at 75°C for 5 minutes. Next, the intermediate layer-forming composition was applied to the shaping film, the substrate was placed on top, and pressure was applied with a roll. Then, ultraviolet light was irradiated from the substrate side to cure the intermediate layer-forming composition. Next, the shaping film was peeled off, and the sheet was heated in an oven at 70°C for 24 hours to obtain an abrasive sheet. Analysis of the three-dimensional elements of the obtained abrasive sheet revealed that, due to the sedimentation of abrasive grains in the recesses, a large number of abrasive grains were present on the apex side.

[0105] (Example A-2) A composition for forming stereochemical elements was prepared by mixing 59.35 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, Arkema), 0.09 parts by mass of silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.), 1.19 parts by mass of photopolymerization initiator (Omunirad 819, IGM Resins), 0.59 parts by mass of photopolymerization initiator (Omunirad 369, IGM Resins), 8.76 parts by mass of diamond abrasive particles (average particle size 15 μm), and 30.03 parts by mass of propylene glycol methyl ether. The ratio of the content of diamond abrasive particles to the content of resin in the composition was 0.14. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0106] (Example A-3) A composition for forming stereochemical elements was prepared by mixing 52.80 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, manufactured by Arkema), 0.16 parts by mass of silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), 1.06 parts by mass of photopolymerization initiator (Omunirad 819, manufactured by IGM Resins), 0.53 parts by mass of photopolymerization initiator (Omunirad 369, manufactured by IGM Resins), 15.59 parts by mass of diamond abrasive particles (average particle size 15 μm), and 29.87 parts by mass of propylene glycol methyl ether. The ratio of the content of diamond abrasive particles to the content of resin in the composition was 0.3. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0107] (Example A-4) A composition for forming stereochemical elements was prepared by mixing 43.07 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, Arkema), 0.25 parts by mass of silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.), 0.86 parts by mass of photopolymerization initiator (Omunirad 819, IGM Resins), 0.43 parts by mass of photopolymerization initiator (Omunirad 369, IGM Resins), 25.42 parts by mass of diamond abrasive particles (average particle size 15 μm), and 29.96 parts by mass of propylene glycol methyl ether. The ratio of the diamond abrasive content to the resin content in the composition was 0.6. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0108] (Example A-5) A composition for forming stereochemical elements was prepared by mixing 23.30 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, manufactured by Arkema), 0.34 parts by mass of silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.46 parts by mass of photopolymerization initiator (Omunirad 819, manufactured by IGM Resins), 0.23 parts by mass of photopolymerization initiator (Omunirad 369, manufactured by IGM Resins), 34.39 parts by mass of diamond abrasive particles (average particle size 15 μm), and 41.27 parts by mass of propylene glycol methyl ether. The ratio of the content of diamond abrasive particles to the content of resin in the composition was 1.4. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0109] (Comparative Example X-1) A composition for forming stereochemical elements was prepared by mixing 67.22 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, Arkema), 0.01 parts by mass of silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.), 1.34 parts by mass of photopolymerization initiator (Omunirad 819, IGM Resins), 0.67 parts by mass of photopolymerization initiator (Omunirad 369, IGM Resins), 0.99 parts by mass of diamond abrasive particles (average particle size 15 μm), and 29.76 parts by mass of propylene glycol methyl ether. The ratio of the diamond abrasive content to the resin content in the composition was 0.014. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0110] (Comparative Example X-2) A composition for forming stereochemical elements was prepared by mixing 65.63 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, Arkema), 0.02 parts by mass of silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.), 1.31 parts by mass of photopolymerization initiator (Omunirad 819, IGM Resins), 0.66 parts by mass of photopolymerization initiator (Omunirad 369, IGM Resins), 1.94 parts by mass of diamond abrasive particles (average particle size 15 μm), and 30.44 parts by mass of propylene glycol methyl ether. The ratio of the diamond abrasive content to the resin content in the composition was 0.028. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0111] (Comparative Example X-3) A composition for forming stereochemical elements was prepared by mixing 17.29 parts by mass of tris(2-hydroxyethyl) isocyanurate triacrylate (SR368, Arkema), 0.51 parts by mass of silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.), 0.31 parts by mass of photopolymerization initiator (Omunirad 819, IGM Resins), 0.17 parts by mass of photopolymerization initiator (Omunirad 369, IGM Resins), 51.06 parts by mass of diamond abrasive grains (average particle size 15 μm), and 30.64 parts by mass of propylene glycol methyl ether. The ratio of the content of diamond abrasive grains to the content of resin in the composition was 2.8. An abrasive sheet was prepared in the same manner as in Example A-1, except that this composition for forming stereochemical elements was used.

[0112] (Evaluation of abrasive sheets) Polishing tests were conducted on the polishing sheets prepared in the examples and comparative examples under the following conditions, and the amount of material removed in 30 seconds (mg / 30 seconds) and the surface roughness Ra (μm) of the resulting smooth surface were determined. Furthermore, polishing tests were conducted 19 times on the same polishing surface under the same conditions, and the amount of material removed in 30 seconds and the surface roughness Ra of the resulting smooth surface were determined for each test. The results for the amount of material removed are shown in Table 1, and the results for the surface roughness Ra are shown in Table 2. • Workpiece: S45C (untreated) • Size of workpiece to be polished: 10mm diameter x 200mm length • Polishing equipment: Super Finisher (manufactured by Matsuda Seiki) • Rotation speed: 829 rpm • Abrasive sheet feed: None Oscillation: None • Grinding fluid: CIMCOOL FLUIDS TECHNOLOGY Co., Ltd. ) 2% aqueous solution • Backup roll hardness: Shore A 30° • Cutting depth: 4.2mm ·Polishing time: 30 seconds • Cut amount: The weight loss of the workpiece after the polishing test was defined as the cut amount. • Average surface roughness Ra: Measured using the following equipment and conditions. Equipment: Mitutoyo Corporation SURFTEST SV-3100H4 Measurement conditions: Compliant with JIS B-0601:2001 (ISO 4287:1997) Cut-off: 0.8mm Evaluation length: 4mm

[0113] [Table 1]

[0114] [Table 2]

[0115] As shown in Tables 1 and 2, in Comparative Examples X-1 and X-2, where the ratio C2 / C1 was less than 0.05, the amount of material removed decreased significantly after fewer than 10 polishing cycles, making polishing difficult. In Comparative Example X-3, where the ratio C2 / C1 was greater than 1.5, the surface roughness Ra gradually increased after more than 10 polishing cycles, making it difficult to form a uniform smooth surface. In contrast, in Examples A-1 to A-5, even after more than 20 polishing cycles, a grinding amount of 3.5 mg / 30 seconds or more and a surface roughness Ra of less than 0.06 μm were maintained, confirming that a uniform smooth surface can be formed even when polishing is performed repeatedly on the same polishing surface. [Explanation of Symbols]

[0116] 10, 20… Abrasive sheets, 11, 21… Base material, 12, 22… Three-dimensional elements, 13, 23… Intermediate layer, 121, 122, 123, 123… Three-dimensional parts.

Claims

1. Substrate and It contains diamond abrasive particles and a binder, and comprises multiple three-dimensional elements that constitute the polishing surface, An intermediate layer is provided between the substrate and the three-dimensional element, and joins the substrate and the three-dimensional element. Includes, The aforementioned binder has a Young's modulus of 1.0 × 10⁹ Pa or higher at 25°C. The aforementioned intermediate layer has a Young's modulus at 25°C of 1.0 × 10⁷ Pa or more and 5.0 × 10⁸ Pa or less. When the three-dimensional element is divided in the thickness direction into a base portion on the substrate side, which accounts for 80 volume percent of the three-dimensional element, and a top portion on the opposite side of the substrate, which accounts for 20 volume percent of the three-dimensional element, at least 50 mass percent of the diamond abrasive grains in the three-dimensional element are located in the top portion. Content C of the aforementioned binder １ The content of the diamond abrasive grains relative to C ２ ratio C ２ / C １ However, the abrasive sheet has a mass ratio of 0.05 to 1.

5.

2. The polishing sheet according to claim 1, wherein the average particle size of the diamond abrasive grains is 5 μm or more.

3. Said ratio C ２ / C １ The abrasive sheet according to claim 1 or 2, wherein the mass ratio is 0.05 to 0.

7.

4. The polishing sheet according to any one of claims 1 to 3, wherein the total volume of the three-dimensional elements is 60 to 90 volume percent of the sum of the three-dimensional elements and the intermediate layer.

5. A polishing method for polishing multiple objects to be polished using a polishing sheet according to any one of claims 1 to 4, A first polishing step involves pressing the polishing surface of the polishing sheet against the object to be polished and sliding the polishing sheet against the object to be polished. A reuse step is performed in which at least a portion of the polished surface used in the first polishing step is used to polish another object to be polished, Polishing methods, including those mentioned above.

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